Differential assembly and vehicle and method for assembling differential assembly

Abstract

The present disclosure relates to a differential assembly (4) comprising: a gearwheel (6) having an axis of rotation (10); a differential spider (12) arranged within the gearwheel (6), with an arm (14) of the differential spider (12) being arranged perpendicular to the axis of rotation (10); a differential pinion (16), which is rotatably arranged on the arm (14) of the differential spider (12); a first output shaft (18) provided with a first differential gear (20); and a second output shaft (22) provided with a second differential gear (24), the first and second output shafts (18, 22) extending concentrically with the rotation axis (10) in opposite directions, and the first and second differential gears (20, 24) being engaged with the differential pinion (16). The inner circumference of the gearwheel (6) is provided with a radially extending recess (26). Each arm (14) of the differential spider (12) engages one of the radially extending recesses (26) via an interference fit.

Description

Technical Field

[0001] The present invention relates to a differential assembly, a vehicle including a differential assembly, and a method for assembling a differential assembly. Background Art

[0002] A differential assembly or device is a gear arrangement that, when subjected to an input speed, provides a speed difference between two output speeds, such as the speeds of two output shafts.

[0003] For example, when the vehicle is turning, the differential assembly may provide a rotational speed difference between two driven wheels on opposite lateral sides of the vehicle.

[0004] DE 102019123969 discloses a method for manufacturing a differential assembly, the method comprising the following steps: providing a first housing and a second housing, each housing having a hollow cylindrical axially outwardly extending support stub at its center; providing a drive wheel blank having a central recess and forming a toothed rim into the outer periphery of the drive wheel blank to obtain a drive wheel; and assembling the housing and the drive wheel to obtain a gear housing rigidly enclosed by the toothed rim. First, the drive wheel blank is press-fitted into the first housing and then the toothed rim is machined into the outer periphery of the drive wheel blank.

[0005] The differential assembly of DE 102019123969 comprises a differential pinion which is rotatably arranged on a rod extending through the drive wheel. The rod is fixed in the differential assembly between a first housing and a second housing. Summary of the invention

[0006] It would be advantageous to achieve an alternative differential assembly. In particular, it would be desirable to achieve a differential assembly that is resistant to internal wear. In order to better address one or more of these problems, one or more of a differential assembly, a vehicle and a method are provided having the features defined in the independent claims.

[0007] According to one aspect, a differential assembly is provided, which includes: a large gear, the large gear being provided with circumferentially extending outer gear teeth and having a rotation axis; a differential cross shaft, the differential cross shaft being arranged inside the large gear, wherein the arms of the differential cross shaft are arranged perpendicular to the rotation axis; a differential pinion gear, the differential pinion gear being rotatably arranged on the arms of the differential cross shaft; a first output shaft provided with a first differential gear; and a second output shaft provided with a second differential gear, the first output shaft and the second output shaft extending in opposite directions concentrically with the rotation axis, and the first differential gear and the second differential gear engaging with the differential pinion gear. The inner circumference of the large gear is provided with radially extending recesses, and each arm of the differential cross shaft engages with one of the radially extending recesses via interference fit.

[0008] Since the inner circumference of the large gear is provided with radially extending recesses and since each arm of the differential cross shaft engages with one of the radially extending recesses via an interference fit, the differential cross shaft is firmly engaged with the large gear. Therefore, no play is provided between the differential cross shaft and the large gear. Since during use of the differential assembly, torque is transmitted from the large gear to the differential gear via the differential cross shaft and the differential pinion, and since the connection between the large gear and the differential cross shaft includes an interference fit, it is ensured that torque transmission does not cause wear between the large gear and the differential cross shaft.

[0009] According to another aspect, a method for assembling a differential assembly is provided. The differential assembly includes: a large gear having an axis of rotation; a differential cross shaft, the differential cross shaft to be arranged inside the large gear, wherein the arms of the differential cross shaft are arranged perpendicular to the axis of rotation; a differential pinion, the differential pinion to be rotatably arranged on the arms of the differential cross shaft; a first output shaft provided with a first differential gear; and a second output shaft provided with a second differential gear, the first output shaft and the second output shaft being configured to extend in opposite directions concentrically with the axis of rotation, and the first differential gear and the second differential gear being configured to engage with the differential pinion. The inner circumference of the large gear is provided with a radially extending recess. The method includes the following steps:

[0010] - Positioning the arms of the differential cross in the radially extending recesses to provide an interference fit between each arm of the differential cross and a respective one of the radially extending recesses.

[0011] Since the arms of the differential cross shaft are positioned in the radially extending recesses to provide an interference fit between each arm of the differential cross shaft and a corresponding one of the radially extending recesses, as described above, the differential assembly assembled in this manner will ensure that during use of the differential assembly, torque transmission between the large gear and the differential cross shaft does not cause wear between the large gear and the differential cross shaft.

[0012] In contrast, in the differential assembly according to the prior art of DE 102019123969 mentioned above, in which the rod on which the differential pinion is arranged is fixed to the assembly via a first housing and a second housing, when the differential pinion is subjected to loads transmitted to the rod, the rod and / or the gearwheel are susceptible to wear at the pocket in which the rod is placed. (The pocket of the gearwheel corresponds to the recess of the gearwheel of the differential assembly discussed herein.)

[0013] In the prior art, the ease of assembly of the journal of the differential pinion in the gearwheel, such as the rod of the differential assembly of DE 10 2019 123 969, has been given priority.

[0014] The present inventors have realised that good wear resistance between the gear wheel and the differential cross shaft is instead achieved if ease of assembly is sacrificed and an interference fit is provided.

[0015] Furthermore, the differential assembly provides an axially compact design of the differential assembly, since the gearwheel may form a radially outer part of the differential assembly, the differential cross shaft engages with the gearwheel and the differential pinion, and the differential gearwheel is arranged radially inside the gearwheel.

[0016] The gear wheel may be a cogwheel wherein the external gear teeth extend radially from the gear wheel.

[0017] In this document, the differential assembly may also be referred to as an assembly for short.

[0018] The basic construction of differential assemblies is well known, and in the art, various terms may be used for differential assemblies and components of differential assemblies, for example, for: differential assembly - differential gear or differential device; gear - final gear or crown wheel or ring gear; differential spider - carrier; differential pinion - differential gear or planet gear or planet gear; and differential gear - sun gear.

[0019] Unless otherwise defined, in this document, the terms axial, axially, axial direction and axial extension refer to directions concentric or parallel to the rotation axis of the gearwheel, and the terms radial, radially, radial direction and radial extension refer to directions perpendicular to the rotation axis of the gearwheel.

[0020] The bull gear may be the final bull gear with which the pinion gears of the powertrain engage.The powertrain may be a powertrain of a land-based vehicle.

[0021] The bull gear may be a final bull gear of a transmission of the powertrain.

[0022] A powertrain may include at least one electric torque-generative unit, such as an electric motor.

[0023] During use of the assembly, and if neither the first gear nor the second gear is stationary, all components of the assembly rotate about the axis of rotation. Specifically, the differential cross, the differential gear, and the output shaft rotate concentrically with the axis of rotation of the gear. Since the arms of the differential cross extend perpendicularly to the axis of rotation of the gear, the axis of rotation of the differential pinion also extends perpendicularly to the axis of rotation of the gear. However, since the differential cross rotates about the axis of rotation, the differential pinion will rotate about the axis of rotation together with the rotating cross.

[0024] The differential cross shaft has four arms, and a differential pinion is rotatably arranged on each arm of the differential cross shaft.

[0025] The first differential gear and the second differential gear may include gear teeth that engage with gear teeth of the differential pinion gear.

[0026] The differential gear and the differential pinion may form bevel gears, wherein the respective rotation axes of the differential pinions are arranged at 90 degrees to the rotation axes of the first and second differential gears and the gearwheel. The differential gear and the differential pinion are conical.

[0027] During use of the assembly, as in any differential assembly, the differential pinions do not rotate about their respective axes of rotation as long as both output shafts rotate in the same direction at the same speed.

[0028] The first output shaft may form one part together with the first differential gear. Alternatively, the first output shaft and the first differential gear may form separate parts which are rotationally locked to each other. This applies to the second output shaft and the second differential gear.

[0029] The center of the large gear is provided with an opening or through hole in the axial direction of the large gear so that the differential cross shaft, the differential pinion gear and at least a part of the differential gear are arranged inside the large gear.

[0030] The radially extending recess of the gearwheel is provided in the material of the gearwheel, ie the radially extending recess is formed in the body of the gearwheel.

[0031] The term interference fit refers to one of three types of engineering fits: clearance fit, locating or transition fit, and interference fit.

[0032] The interference fit may be achieved by pressing the outer ends of the arms of the differential cross into the radially extending recesses of the gearwheel. Alternatively, the differential cross may be cooled and / or the gearwheel heated before assembling the differential cross in the radially extending recesses of the gearwheel.

[0033] Thus, the step of positioning the arms of the differential cross in the radially extending recesses of the method may include one or more of the following steps:

[0034] - pressing the arms of the differential cross into the radially extending recesses to provide an interference fit, and / or

[0035] - Cooling the differential cross and / or heating the gear wheel before assembling the differential cross in the radially extending recess of the gear wheel, thereby providing a clearance fit once the differential cross and the gear wheel have the same temperature.

[0036] According to some embodiments, the differential assembly may include a first differential housing half and a second differential housing half, which are fixedly mounted to the large gear and can enclose the differential cross shaft, the differential pinion, and the first differential gear and the second differential gear from opposite sides along the rotation axis together with the large gear. The first output shaft can extend through the first differential housing half and the second output shaft extends through the second differential housing half. The first differential housing half can be provided with a first set of axial recesses at the axial end facing the large gear. The arm of the differential cross shaft can engage with the first set of axial recesses. The second differential housing half can be provided with a second set of axial recesses at the axial end facing the large gear and the arm of the differential cross shaft can engage with the second set of axial recesses. In this way, via the engagement of the arm of the differential cross shaft with the first set of axial recesses of the first differential housing half, a direct transmission of torque between the first housing half and the differential cross shaft can be provided, for example. This can be used, for example, under certain operating conditions of the differential assembly, such as when the differential assembly is locked. See below for details.

[0037] Therefore, as described above, the differential cross shaft, the differential pinion, and at least a portion of the first differential gear and the second differential gear can be arranged in the large gear. Therefore, the first differential housing half and the second differential housing half together with the large gear can enclose the differential cross shaft, the differential pinion, and the first differential gear and the second differential gear.

[0038] The arms of the differential cross shaft can extend in the axial direction outside the radial recesses of the large gear so that the arms of the differential cross shaft engage with the first set of axial recesses in the first differential housing half and / or so that the arms of the differential cross shaft engage with the second set of axial recesses in the second differential housing half.

[0039] According to some embodiments, the first differential housing half and the second differential housing half can be connected to each other via bolts, which extend through the gearwheel parallel to the axis of rotation. In this way, the first differential housing half and the second differential housing half can be pressed against the gearwheel. Moreover, by connecting the first differential housing half and the second differential housing half to each other via bolts, the first set of axial recesses of the first differential housing half can be engaged with the arms of the differential cross shaft and / or the second set of axial recesses of the second differential housing half can be engaged with the arms of the differential cross shaft.

[0040] According to some embodiments, the differential assembly may include: a locking sleeve, the locking sleeve being arranged concentrically around the first output shaft; and an interface for releasable engagement between the locking sleeve and the first differential housing half, wherein the locking sleeve can be rotationally locked to the first output shaft and can be moved along the rotation axis to engage and release the interface. In this way, the differential assembly can be locked by engaging the interface between the first output shaft and the first differential housing half. Conversely, the differential assembly can be unlocked by releasing the interface between the first output shaft and the first differential housing half.

[0041] When the differential assembly is locked, the first output shaft and the second output shaft are locked relative to each other so that they can only rotate at the same speed. When the differential assembly is unlocked, the first output shaft and the second output shaft can rotate at different speeds and the differential assembly provides its intended function as a differential device.

[0042] According to some embodiments, the radially outer end of each arm of the differential cross shaft may include two surfaces extending parallel to each other. An interference fit may be provided between the two surfaces and the matching parallel surfaces of the associated radial recess. In this way, an interference fit may be provided between the two parallel surfaces of the radially outer end of the differential cross shaft and the surface of the radial recess at least partially defining the inner circumference of the large gear.

[0043] According to an embodiment, the radially outer end of each arm of the differential cross shaft may include two surfaces extending substantially parallel to each other. Likewise, an interference fit may be provided between the two surfaces and the mating surfaces of the associated radial recesses. In this way, an interference fit may be provided between the two substantially parallel surfaces of the radially outer end of the differential cross shaft and the surface of the radial recess at least partially delimiting the inner circumference of the gearwheel.

[0044] For example, two surfaces extending substantially parallel to each other may extend at an angle in the range of 0.01-2 degrees relative to each other. In this way, compensation may be provided when the arms of the differential cross-shaft bend under load. This is due to a more uniform distribution of pressure on the contact surface between one of the two substantially parallel surfaces of the radially outer end of the differential cross-shaft and one of the surfaces at least partially defining the radial recess at the inner circumference of the gearwheel.

[0045] According to some embodiments, each of the two surfaces of the radial outer end of each arm of the differential cross shaft can be a convex surface. In this way, the assembly of the differential cross shaft in the radial recess of the large gear can be facilitated, although the fit between the arms of the differential cross shaft and the radial recess is an interference fit.

[0046] That is, since each of the two surfaces is a convex surface, a portion of the radially outer end of each arm of the differential cross shaft can be more easily positioned in the associated radial recess during assembly of the differential cross shaft in the gearwheel than in the case where an interference fit is provided by engagement between flat surfaces. This is because the interference fit can be achieved by the widest portion of the radially outer end of the associated arm of the differential cross shaft, which is formed between the highest portions of the two convex surfaces of the radially outer end of the associated arm.

[0047] According to some embodiments, the convex surface may be convex in the range of 0.02%-1% along the length of the convex surface extending in the tangential direction. In this way, a suitable convexity may be provided.

[0048] According to some embodiments, with the locking sleeve engaged with the interface between the first differential housing half, the differential assembly can transfer torque between the first output shaft and the second output shaft via the first differential gear, the locking sleeve, the interface, the first differential housing half, the first set of axial recesses of the first differential housing half, the differential cross shaft, and the second differential gear. In this way, when the differential assembly is locked, at least a portion of the torque can be directly transferred to the differential cross shaft between the first differential gear and the second differential gear via the first differential housing half, rather than via the differential gear and the differential pinion.

[0049] According to another aspect, there is provided a vehicle comprising a powertrain including a differential assembly according to any of the aspects and / or embodiments discussed herein.

[0050] Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Various aspects and / or embodiments of the present invention, including specific features and advantages thereof, will be readily understood from the example embodiments discussed in the following detailed description and accompanying drawings, in which:

[0052] Figure 1 shows a vehicle according to some embodiments,

[0053] Figure 2 schematically illustrates an embodiment of a powertrain for a vehicle,

[0054] Figure 3a-3c showing various views of a differential assembly according to some embodiments,

[0055] Figure 4a-4c A portion of a differential cross shaft is schematically shown,

[0056] Figure 5 A method for assembling a differential assembly is shown. DETAILED DESCRIPTION

[0057] Aspects and / or embodiments of the present invention will now be described in more detail. Like reference numerals refer to like elements throughout. For the sake of brevity and / or clarity, well-known functions or configurations will not necessarily be described in detail.

[0058] Figure 1 An embodiment of a vehicle 2 configured for land-based propulsion is schematically shown. The vehicle 2 includes a differential assembly according to any of the aspects and / or embodiments discussed herein, for example, as described below with reference to Figure 2-4b The differential assembly 4 is discussed.

[0059] In these embodiments, the vehicle 2 is a heavy vehicle in the form of a truck. However, the invention is not limited to any particular type of vehicle configured for land-based propulsion.

[0060] The vehicle 2 includes a powertrain including a differential assembly. The powertrain may include at least one electric machine.

[0061] Figure 2 An embodiment of a powertrain 11 of a vehicle is schematically shown.

[0062] The powertrain 11 may be used as described above with reference to Figure 1 A powertrain 11 of the vehicle 2 or any other type of vehicle configured for land-based propulsion is discussed.

[0063] The powertrain 11 includes an electric machine 3 (e.g., a motor / generator), at least one transmission 5, a final drive 7, a differential assembly 4 as discussed herein, and two drive shafts 9. Torque provided by the electric machine 3 is transmitted to the final drive 7 and the differential assembly 4 via the at least one transmission 5. From the differential assembly 4, the torque is distributed between each drive shaft 9 to drive the wheels of the vehicle to propel the vehicle.

[0064] The differential assembly 4 may be used in other types of drivetrains other than the drivetrain 11 shown.

[0065] Figure 3a-3c Various views of a differential assembly 4 are shown according to some embodiments. Figure 3a An exploded view of the differential assembly 4 is shown. Figure 3b An exploded view of a portion of the differential assembly 4 is shown. Figure 3c A cross-sectional side view along an axis of rotation 10 passing through the differential assembly 4 is shown.

[0066] The differential assembly 4 may be configured to form part of a powertrain of a vehicle, for example Figure 1 and Figure 2 The vehicle 2 and powertrain 11 are discussed. The assembly 2 may be based on the following reference Figure 5 The method 100 is discussed for assembly.

[0067] The assembly 4 comprises a gearwheel 6 , a differential cross shaft 12 arranged inside the gearwheel 6 , a differential pinion 16 , a first output shaft 18 provided with a first differential gear 20 , and a second output shaft 22 provided with a second differential gear 24 .

[0068] The gearwheel 6 is provided with circumferentially extending outer gear teeth 8. The gearwheel 6 has a rotation axis 10. A differential cross shaft 12 is arranged in a central opening 13 of the gearwheel 6. Furthermore, a differential pinion 16 and at least a part of the differential gears 22, 24 may be arranged in the opening 13.

[0069] The arms 14 of the differential cross shaft 12 are arranged perpendicular to the rotation axis 10, that is, the arms 14 extend radially from the rotation axis 10. The differential pinions 16 are rotatably arranged on the arms 14 of the differential cross shaft 12. That is, one differential pinion 16 is journaled on each arm 14 of the differential cross shaft 12.

[0070] Each differential pinion 16 therefore rotates about a respective axis of rotation 17 coinciding with the radial extension of one of the arms 14 of the differential cross 12 .

[0071] The differential cross shaft 12 has four arms 14 , and a differential pinion 16 is rotatably arranged on each arm 14 of the differential cross shaft 12 .

[0072] The first output shaft 18 and the second output shaft 22 extend in opposite directions concentrically with the rotation axis 10. The first differential gear 20 and the second differential gear 24 engage with the differential pinion 16. The first differential gear 20 and the second differential gear 24 include gear teeth that engage with gear teeth of the differential pinion 16.

[0073] In the embodiment shown, the first and second output shafts 18, 22 each form one part together with the respective first and second differential gears 20, 24. Alternatively, the shafts 18, 22 may form separate parts rotationally locked to the differential gears 20, 24.

[0074] In the illustrated embodiment, the first output shaft 18 and the second output shaft 22 are hollow, wherein the respective shafts 28, 30 extend into the hollow first output shaft 18 and the second output shaft 22 and are rotationally locked in the first output shaft 18 and the second output shaft 22, see Figure 3c Thus, the shafts 28, 30 are arranged to transmit the rotation of the first output shaft 18 and the second output shaft 22 to the drive wheels of the vehicle. Alternatively, the first output shaft 18 and the second output shaft 22 may extend along the rotation axis 10 longer than Figure 3cThe shaft 28, 30 is shown longer in order to transmit its rotation to the drive wheels of the vehicle without corresponding shafts 28, 30.

[0075] The inner circumference of the large gear 6 is provided with radially extending recesses 26. Each arm 14 of the differential cross shaft 12 engages with one of the radially extending recesses 26 via an interference fit.

[0076] Merely as examples, the outer diameter of the large gear 6 can be in the range of 200-400 mm, the differential cross shaft 12 can have an extension in the range of 120-200 mm between the ends of the relatively extending arms 14, the arms 14 of the differential cross shaft 12 can have a diameter in the range of 30-50 mm, wherein the differential pinion 16 is journaled on the arms 14, and the interference fit can be a fit with a tolerance of H7 / p6 or H7 / s6 or a fit with a tolerance of P7 / h6 or S7 / h6.

[0077] The differential assembly 4 includes a first differential housing half 34 and a second differential housing half 36 which are fixedly mounted to the large gear 6 and together with the large gear 6 enclose the differential cross shaft 12, the differential pinion 16 and the first differential gear 20 and the second differential gear 24 from opposite sides along the rotation axis 10.

[0078] The first output shaft 18 extends through the first differential housing half 34 and the second output shaft 22 extends through the second differential housing half 36. For this purpose, each of the first housing half 34 and the second housing half 36 is provided with a through hole 38, 40 which is concentric with the axis of rotation 10.

[0079] During use of the assembly 4, the first housing half 34 and the second housing half 36 rotate together with the gearwheel 6. As long as the first output shaft 18 and the second output shaft 22 rotate at the same speed, the shafts 18, 22, the first housing half 34 and the second housing half 36, and the gearwheel 6 rotate at the same speed. When the first output shaft 18 and the second output shaft 22 rotate at different speeds, the shafts 18, 22 rotate in the through holes 38, 40 relative to the first housing half 34 and the second housing half 36.

[0080] The first differential case half 34 is provided with a first set of axial recesses 42 at an axial end of the first differential case half 34 facing the gearwheel 6. The arms 14 of the differential cross shaft 12 engage with the first set of axial recesses 42.

[0081] The second differential case half 36 is provided with a second set of axial recesses 44 at the axial end of the second differential case half 36 facing the large gear wheel 6. The arms 14 of the differential cross shaft 12 engage with the second set of axial recesses 44.

[0082] That is, a portion of the large gear 6 is dimensioned in the axial direction such that the arms 14 of the differential cross shaft 12 extend axially outside the radially extending recesses 26 of the large gear 6. Therefore, the first differential case half 34 and the second differential case half 36 fixedly mounted to the large gear 6 will provide the arms 14 of the differential cross shaft 12 to engage with the first set of axial recesses 42 and the second set of axial recesses 44.

[0083] The first differential case half 34 and the second differential case half 36 are connected to one another via bolts 46 which extend through the gearwheel 10 parallel to the axis of rotation 10 .

[0084] As in the illustrated embodiment, bolts 46 extend through holes in second differential case half 36 and holes in gear 6 to threadedly engage threaded holes in first differential case half 34. Thus, first and second differential case halves 34, 36 are fixedly mounted to gear 6.

[0085] Alternative ways of fixedly mounting the first and second differential case halves 34, 36 to the gear 6 are contemplated. Separate bolts may extend through each of the case halves 34, 36 and threadedly engage the gear 6. Another alternative may be for the bolts to extend through the case halves 34, 36 and the gear 6 and be tightened with nuts.

[0086] The differential assembly 4 includes a locking sleeve 48 disposed concentrically about the first output shaft 18 and an interface 50 for releasable engagement between the locking sleeve 18 and the first differential housing half 34. The locking sleeve 48 is rotationally locked to the first output shaft 18 and is movable along the rotational axis 10 to engage and release the interface 50.

[0087] The interface 50 includes teeth 52 extending axially from the locking sleeve 48 and from the first differential housing half 34. Moving the locking sleeve 48 axially toward the first differential housing half 34 will cause the teeth 52 to engage one another and thus will engage the interface 50. Moving the locking sleeve 48 axially away from the first differential housing half 34 will cause the teeth 52 to release one another and thus will release the interface 50.

[0088] The locking sleeve 48 may be rotationally locked to the first output shaft 18 via splines. Such splines will allow axial movement of the locking sleeve 48 on the first output shaft 18.

[0089] When the interface 50 is engaged, the differential assembly 4 is locked. When the interface 50 is released, the differential assembly 4 is unlocked. Figure 3c In the process, the interface 50 is released.

[0090] During use of the assembly 4, with the locking sleeve 48 engaged with the interface 50 between the first differential housing half 34, torque can be at least partially transmitted between the first output shaft 18 and the second output shaft 22 via the locking sleeve 48, the interface 50, the first differential housing half 34, the first set of axial recesses 42 of the first differential housing half 34, the differential cross shaft 12, the differential pinion 16, and the second differential gear 24.

[0091] In the interface 50 , torque is transferred between teeth 52 of the locking sleeve 48 and teeth 52 of the first differential case half 34 .

[0092] Figure 4a-4c A portion of an arm 14 of the differential cross-shaft 12 of the differential assembly 4 discussed above is schematically illustrated. Figure 4a and 4b A side view of an end portion of the arm 14 is shown, ie a view towards the axis of rotation 17 of the differential pinion. Figure 4c A partial end view of an end portion of the arm 14 is shown, ie a view along the axis of rotation 17 of the differential pinion.

[0093] The radially outer end of each arm 14 of the differential cross 12 comprises two surfaces 54 extending parallel to each other. The two surfaces 54 may extend parallel to the axis of rotation 17 of a differential pinion (not shown) to be journaled on the arm 14.

[0094] The interference fit between the radially extending recess 26 in the gear wheel 6 and each arm 14 of the differential cross shaft 12 discussed herein is provided between two surfaces 54 of each arm 14 of the differential cross shaft 12 and the mating parallel surfaces of the associated radial recess 26, see also Figure 3a .

[0095] like Figure 4a As indicated by dashed lines in FIG. 1 , the radially outer end of each arm 14 of the differential cross shaft 12 may include two surfaces 54 extending at an angle α in the range of 0.01-2 degrees relative to each other. Likewise, an interference fit is provided between the two surfaces 54 and the mating surfaces of the associated radial recess 26. Thus, the two surfaces 54 at the radially outer end of each arm 14 of the differential cross shaft 12 may extend substantially parallel to each other.

[0096] In other words, each surface 54 may extend at an angle α / 2 relative to the axis of rotation 17 of the differential pinion.

[0097] For clarity, the angle α is Figure 4a has been exaggerated.

[0098] According to some embodiments, each of the two surfaces 54 of the radially outer end of each arm 14 of the differential cross shaft 12 may be a convex surface, such as Figure 4band / or Figure 4c Regardless of whether the two surfaces 54 extend parallel to each other or substantially parallel to each other, the surfaces 54 may be convex surfaces.

[0099] In such embodiments with convex surfaces, the plane of each of the two surfaces 54 can be a tangential plane to the associated surface 54. Thus, if the tangential planes of the two convex surfaces 54 extend in parallel, then the two surfaces 54 are parallel. Similarly, the angle α between the two convex surfaces 54 is determined by the angle α between the tangential planes of the two convex surfaces 54.

[0100] Each convex surface 54 may be convex in the range of 0.02%-1% along the length L of the convex surface 54 extending in the tangential direction.

[0101] More specifically, the convexity is calculated by the ratio of the height H of the highest point of the convex surface 54 above a flat surface extending between the endpoints of a length L extending tangentially along the convex surface 54 .

[0102] Therefore, 0.02% <H / L<1%。

[0103] The extension of the convex surface 54 may be parallel to the axis of rotation 17 of the differential pinion, such as Figure 4b Alternatively, the extension of the convex surface 54 may be an extension across the axis of rotation 17 of the differential pinion, as shown in Figure 4c as shown in .

[0104] According to some embodiments, the convex surface 54 is convex in only one direction, ie parallel to or straddling the rotation axis 17 of the pinion.

[0105] According to some embodiments, the convex surface 54 convexly projects in two directions, ie parallel to the pinion's axis of rotation 17 and straddling the pinion's axis of rotation.

[0106] Therefore, the interference fit will be provided at least at the widest part of the two convex surfaces 54 at the radial outer end of the arm 14 and the radial recess 26 of the gearwheel 6. The widest part between the two convex surfaces 54 will be between the highest points of the two parallel convex surfaces 54.

[0107] Figure 5 A method 100 for assembling a differential assembly is shown. The differential assembly may be an assembly 4 according to any of the aspects and / or embodiments discussed herein. Therefore, reference is also made hereinafter to Figure 1-4b .

[0108] Therefore, the differential assembly 4 includes: a large gear 6 having a rotation axis 10; a differential cross shaft 12 to be arranged inside the large gear 6, wherein the arm 14 of the differential cross shaft 12 is arranged perpendicular to the rotation axis 10; a differential pinion 16 to be rotatably arranged on the arm 14 of the differential cross shaft 12; a first output shaft 18 provided with a first differential gear 20; and a second output shaft 22 provided with a second differential gear 24. The first output shaft 18 and the second output shaft 22 are configured to extend in opposite directions concentrically with the rotation axis 10, and the first differential gear 20 and the second differential gear 24 are configured to engage with the differential pinion 16. The inner circumference of the large gear 6 is provided with a radially extending recess 26.

[0109] The method 100 comprises the following steps:

[0110] Positioning 102 the arms 14 of the differential cross 12 in the radially extending recesses 26 to provide an interference fit between each arm 14 of the differential cross 12 and a respective one of the radially extending recesses 26 .

[0111] The step of positioning 102 the arms 14 of the differential cross-shaft 12 in the radially extending recesses 26 may include the following steps:

[0112] - Pressing 104 the arms 14 of the differential cross 12 into the radially extending recesses 26 to provide an interference fit.

[0113] According to some embodiments, prior to the step of positioning 102 arms 14 of differential cross-shaft 12 in radially extending recesses 26 , method 100 may include one or more of the following steps:

[0114] - Cooling 106 the differential cross-shaft 12 and / or heating 108 the gear wheel 6 in order to provide a clearance fit once the differential cross-shaft 12 and the gear wheel 6 have the same temperature.

[0115] It should be understood that the above is an illustration of various example embodiments, and the present invention is limited only by the appended claims. Those skilled in the art will recognize that the example embodiments may be modified without departing from the scope of the present invention as defined by the appended claims, and that different features of the example embodiments may be combined to form embodiments other than those described herein.

Claims

1. A differential assembly (4), comprising: a large gear (6) provided with circumferentially extending outer gear teeth (8) and having a rotation axis (10); A differential cross shaft (12), the differential cross shaft being arranged in the large gear (6), wherein the arm (14) of the differential cross shaft (12) is arranged perpendicular to the rotation axis (10); a differential pinion gear (16), the differential pinion gear being rotatably arranged on the arm (14) of the differential cross shaft (12); a first output shaft (18) provided with a first differential gear (20); and a second output shaft (22) provided with a second differential gear (24), the first output shaft and the second output shaft (18, 22) extending in opposite directions concentrically with the rotation axis (10), and the first differential gear and the second differential gear (20, 24) being engaged with the differential pinion gear (16), wherein The inner circumference of the large gear (6) is provided with a radially extending recess (26), and wherein Each arm (14) of the differential cross (12) engages one of the radially extending recesses (26) via an interference fit.

2. The differential assembly (4) according to claim 1, comprising a first differential housing half (34) and a second differential housing half (36), wherein the first differential housing half and the second differential housing half are fixedly mounted to the large gear (6) and together with the large gear (6) enclose the differential cross shaft (12), the differential pinion (16) and the first differential gear and the second differential gear (20, 24) from opposite sides along the rotation axis (10), wherein The first output shaft (18) extends through the first differential housing half (34) and the second output shaft (22) extends through the second differential housing half (36), wherein The first differential housing half (34) is provided with a first set of axial recesses (42) at the axial end facing the large gear (6), wherein The arms (14) of the differential cross (12) engage the first set of axial recesses (42), wherein The second differential housing half (36) is provided with a second set of axial recesses (44) at the axial end facing the large gear (6), wherein The arms (14) of the differential cross (12) engage the second set of axial recesses (44).

3. The differential assembly (4) according to claim 2, wherein the first differential housing half (34) and the second differential housing half (36) are connected to each other via bolts (46), which extend through the large gear (6) parallel to the rotation axis (10).

4. A differential assembly (4) according to any one of the preceding claims, comprising a locking sleeve (48) arranged concentrically around the first output shaft (18) and an interface (50) for releasable engagement between the locking sleeve (48) and the first differential housing half (34), wherein the locking sleeve (48) is rotationally locked to the first output shaft (18) and is movable along the rotation axis (10) to engage and release the interface (50).

5. A differential assembly (4) according to any one of the preceding claims, wherein the radially outer end of each arm (14) of the differential cross shaft (12) includes two surfaces (54) extending parallel to each other, and wherein the interference fit is provided between the two surfaces (54) and the mating parallel surfaces of the associated radial recess (26).

6. A differential assembly (4) according to any one of claims 1 to 4, wherein the radially outer end of each arm (14) of the differential cross shaft (12) comprises two surfaces (54) extending at an angle (α) in the range of 0.01-2 degrees relative to each other, and wherein the interference fit is provided between the two surfaces (54) and the mating surfaces of the associated radial recess (26).

7. The differential assembly (4) according to claim 5 or 6, wherein each of the two surfaces (54) of the radially outer end of each arm (14) of the differential cross-shaft (12) is a convex surface (54).

8. The differential assembly (4) of claim 7, wherein the convex surface (54) is convex in the range of 0.02%-1% along a length of the convex surface (54) extending in a tangential direction.

9. A differential assembly (4) according to claims 2 and 4 or according to claims 2 and 4 and any one of claims 5-8, wherein when the interface (50) between the locking sleeve (48) and the first differential housing half (34) is engaged, torque can be transmitted between the first output shaft and the second output shaft (18, 22) via the locking sleeve (48), the interface (50), the first differential housing half (34), the first set of axial recesses (42) of the first differential housing half (34), the differential cross shaft (12), and the second differential gear (24).

10. A vehicle (2) comprising a powertrain (11) including a differential assembly (4) according to any one of the preceding claims.

11. A method for assembling a differential assembly (4), the differential assembly (4) comprising: A gearwheel (6) having an axis of rotation (10); A differential cross shaft (12), the differential cross shaft is to be arranged in the large gear (6), wherein the arm (14) of the differential cross shaft (12) is arranged perpendicular to the rotation axis (10); a differential pinion (16), the differential pinion is to be rotatably arranged on the arm (14) of the differential cross shaft (12); a first output shaft (18) provided with a first differential gear (20); and a second output shaft (22) provided with a second differential gear (24), the first output shaft and the second output shaft (18, 22) are configured to extend in opposite directions concentrically with the rotation axis (10), and the first differential gear and the second differential gear (20, 24) are to engage with the differential pinion (16), wherein the inner circumference of the large gear (6) is provided with a radially extending recess (26), and wherein the method comprises the following steps: - positioning (102) the arms (14) of the differential cross (12) in the radially extending recesses (26) to provide an interference fit between each arm (14) of the differential cross (12) and a respective one of the radially extending recesses (26).

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